Download IB Biology Chapter - Fredericksburg City Schools

IB Biology Chapter 4
Ecology
Species ,communities, and
ecosystems
• Interdependence of Living Organisms
• 1980-eruption @ Mt St. Helen’s-see p.172
What is a species?
• Defined as a _____________________
• Made up of organisms that• Have similar physiological and morphological
(ie. Size and shape of an organism and/or its
parts) characteristics that can be observed or
measured
• Have the ability to interbreed and produce
fertile offspring
• Are genetically distinct from other organisms
• Have a common phylogeny(ie.family tree)
That can
interbreed and
produce fertile
offspring
• Challenges to this definition:
• Sometimes members of separate but similar species mate
and succeed in hybrid offspring-eg.horse+zebra-produces--zebroids-both parents belong to Equidae family-related
but not same species-do not have same # c’somes-why
offspring usually infertile
• Some populations may be able to interbreed,but do not
do so because they are in different niches or separated by
long distances
• How do we classify organisms that reproduce asexually
• What about infertile offspring-Do we exclude humans
unable to reproduce from species?
• What about in vitro fertilization
• Domesticated dogs-while different breeds-are same
species and can interbreed
Hybrids
• To understand fertile offspring-♀(female) horse +
♂(male) produce_____-mules cannot mate to make
more mules-mule is ∴
called_____________________________________
• ♂lion and ♀ tiger produce liger hybrid
• Challenges hybrids face cont as a population
inc.infertilty,
• Other hybrids:
• ♀ horse + ♂ donkey=mule
• ♀ horse + ♂ zebra=zorse
• ♀ tiger + ♂ lion=liger
mule
Interspecific hybrid
Populations can become isolated
• Grp from a species separated from rest of species may
evolve differently when compared w/rest of populationeg.mice have inadvertently crossed oceans on board ships-as
they searched for food-may even end up islands away-mice
produced on new islands are reproductively isolated-may
end up w/ a different frequency of certain alleles-eg fur
color
• Other things can produce isolation-such as mt. ranges-tree
snails in Hawaii-present on only one side of volcano
• Also temporal isolation-early migrating birds may have
genes isolated from later arrivals
• Behavioral isolation-such as different mating calls from same
species of birds
• Over time-some of these may result in speciation_________________________________(refer to ch 10.3)
New species formed from old
Autotrophs and heterotrophs
• Autotrophs-capable of ________
-synthesize organics from simple inorganicsusually by photosynthesis
• Because the food they make is eaten by
others
• __________
• Examples-cyanobacteria,algae,grass,trees
photosynthesis
producers
• Heterotrophs—cannot make own food from inorganics-but
must get from other organisms-from autotrophy and
heterotrophy-called ____________________because rely on
others, ingest organic matter
• -Examples-zooplankton, fish, sheep, insects
consumers
E. Consumers
• Heterotrophs-whether we from autotrophs or products of
other heterotrophs
• Take in energy-rich C-compounds, such as
sugars,proteins,and lipids
• Only part of human’s diet that we synthesize is Vitamin D cholesterol molecule in our skin is modified by light into
Vitamin D
• Detritivores
• Eat non-living organic matter-dead leaves,
feces, carcasses-eg. Earthworms,woodlice
Saprotrophs
• Live on or in non-living organic matter,
secreting enzymes and absorbing the
products of digestion
• Fungi, some bacteria-decomposers
Communities
• Group of populations living and interacting with
each other in an area
• 1 species may interact by feeding on another or
being eaten
• May provide vital nutrients for another(e.g.-Nfixing bacteria)
• One species may provide protection for anothere.g.-aphids protected by ants
• One may rely on another for its habitat-e.g.parasites
Ecosystems
abiotic
• ______________-non-living components of
environment(air,water,rocks)-such measurements include
_______________-often using electronic probes and data-logging
techniques
• These things have a large influence on living things
• ________________-living factors
• Random sampling using quadrats(to determine the frequency and
distribution of a species)-see page 178
• Systematic sampling-using a transect= a line traced from one
environment to another-may be a 1,25-50 m long-may set up
quadrat every meter along transect or at specific intervals along
transect-counting the organisms that hit each quadrat and then
counting organisms found in each quadrat-no random
numbers….see p. 179
Temp,pH,light
levels,and
relative humidity
biotic
Where do autotrophs get their
nutrients?
• From inorganic surroundings
• Photosynthetic organismsphytoplankton,cyanobacteria,and plants--photosynthesis
• Producers and start of food chain
Nutrient Cycling
•
•
•
•
•
•
•
•
•
Find need nutrients w/in own habitat-C,N,etc
Decomposers
Accessing nutrients through decay
Saprophytes and detritivores break down body parts of dead organisms
Digestive enzymes convert organic matter into more usable forms for
themselves and other organisms-e.g. proteins from dead organisms are
broken down into ammonia(NH3) and then, in turn ammonia has its N
converted into nitrates(NO3-) by bacteria.
This recycles nutrients so they are available to other organisms-instead
of locked into carcasses or waste products
Decomposers help w/formation of soil
________-rich black layer composed of organic debris and nutrients
released by decomposers
Decomposers form humus in compost piles
compost
The sustainability of ecosystems
• Through recycling of nutrients, ecosystems can contribute to
be productive and successful for long periods of time
• Convert CO2 to C6H12O6-by producers-used then to make
complex carbs-like cellulose –or lipids and proteins
• Consumers eat producers, and digest the complex organic
compounds into simple building blocks---amino acids and
sugars,eg,for growth and energy
• When the consumers die,their cells and tissues are broken
down by decomposers-minerals ret’d to soil---for producers
,once again-completing cycle
• N-cycle-N important for nucleotides and amino acids—
essential to DNA and proteins-essential to existence
• Cycle starts w/ N in gas form in atmosphere(N2)—Plants and
animals can’t use N2—some bacteria transform it by N-fixing
Then absorbed by plant roots(some plants have N-fixing
nodules attached to roots)----Plants and animals return N to
soil in variety of ways—e.g. ,ret’d by
decomposition,byurine,feces
Energy Flow
• Importance of sunlight to ecosystems
• Best studied ecosystems on earth’s surface,
relying on sunlight-are the focus here
• All life relies directly or indirectly on sun
B. Role of photosynthesis
• Take CO2 and convert to C6H12O6
• Light energy converts into chemical
energy(food)-rich in energy due to chemical
bonds between C and other atoms
• Chemical energy measured in calories or
kilocalories(kilocalories on pkg’ing)
• Release energy by digesting,also to burn
Food chain
Process of passing
energy from one
organism to
another
• Food chain defined as _______-arrow shows direction of
energy flow
• Trophic level=indicates how many organisms the energy has
flowed through
• 1st trophic level has autotrophs or prodcers;next level
primary consumers; next secondary consumers
Sequence showing
feeding
relationships band
energy flow
between species
Cellular respiration and heat
• As grasshoppers consume grass, chemical energy
is used for cellular respiration/glucose converted
to CO2 and H2O
• This takes a sm amount of heat in each of
grasshoppers cells…heat lost to
environment/thee nutrient and energy passed on
to next consumers
• Cells of decomposers also do cellular respiration
and thus release heat to environment
Heat cannot be recycled
• Heat not actually lost due to law
of conservation of energy, but
cannot be used again as
biological energy source
Where does the heat go?
• Heat lost from ecosystem, radiates into surrounding
environment/ecosystem cannot take back heat to use
it-not recycled like nutrients
• Food chain only adversely affected by the lost heat if
sun is lost-thus affecting food chains
• Only chemical energy can be used by next trophic
level and only a small amount of energy absorbed is
converted into chemical energy
• No organism can use 100% of energy in organic
molecules-typically only 10-20% used from previous
step…~ 90% lost
Main reasons not all energy in n organism can be used
by all other trophic levels:
• Not all of an organism is swallowed as a food sourcesome parts rejected and decay
• Not all food swallowed can be absorbed and used in
body(e.g.-owl pellets)
• __________________
• There is considerable heat loss from cellular respiration
@ all trophic levels-most animals have to moverequiring more energy than plants-Warm blooded
animals use much more
Some organisms die
w/o having been eaten
by member of next
trophic level
see p.188
Pyramid of energy
• Used to show how much and how fast energy
flows from one trophic level to the next in a
community
• Units=energy per unit area per
time=kilojoules per square meter per
year(kjm-2yr-1)—take into account rate of
energy produced as well qty
Because energy is lost-each level smaller than
previous—cannot have higher level wider than
lower level
Food webs and energy levels in trophic levels
• # of organisms in a chain as well as qty sunlight energy available @
start decide length of chain
• Biomass of a trophic level=estimate of mass of all organisms w/in
that level-expressed in mass units, but also take into account area or
volume eg.3tons acre• 1yr-1
• Amount of sunlight reaching fields affects biomass, therefore sunnier
region produce more biomass wheat
• Some molecules along the way cannot participate in biomass because
they re lost-e.g. CO2 lost in cellular respiration, water during
transpiration evapoartion from skin,urea lot in excretion• ∴not all energy passed to next trophic level and not all biomass
passed on
• Sometimes foodweb rather than chain is used because there may be
many feeding relationships going on
III. Carbon cycling
• Crucial element to life
• Life on earth is referred to as C-based
• In biosphere as carbs, lipids, nucleic acids and
proteins
• Also in atmosphere as CO2 and lithosphere
____________________________
i.e.-places where rocks
are found .
• Petroleum-from which gasoline, kerosene, and
plastics are made-rich in C having come from
decomposed organisms of millions of years ago
• Constantly cycled between living organisms and
inorganic processes making C available-e.g. C atoms
composing the flesh of a giraffe come from the
vegetation it ate
• When cellular respiration is complete-CO2 released
into atmosphere
• When organisms die, scavengers eat decomposers
break down—which release CO2 back into
atmosphere from cellular respiration
• Glucose also starting point for other organicse.g. lipids and amino acids-which go into cell
membranes and proteins-enzymes
• Other elements added to glucose-such as N
C in aquatic ecosystems
• CO2 water soluble
• Absorbed by bodies of water
• Organisms living in water also produce CO2
(by cellular respiration)
• ____________________________
As CO2 is dissolve in water it forms an aciddecreasing water’s pH
The H+ influences pH
The HCO3 – important inorganic C-based molecule
that participates in C-cycle
Cycling of CO2
 Absorbed by photosynthetic
autotrophs such as bacteria,
phytoplankton, plants, and trees.
They are eaten by consumers,
using C in their bodies
 Cellular respiration (hereby
abbreviated as cr) from all trophic
levels produce CO2-releasing it
back into environment
 Diffuses into atmosphere or into
water
Methane in C-cycle
• Members of Archaea include methanogensanaerobic
• ___________________________
• Methanogens also common in wetlands,
where they produce marsh gas (may glow)
• Also produce CH4 in digestive tract of
mammals-inc. humans-hence the concern
w/cattle herds-contribute to greenhouse
effect (next section)
When they metabolize food, they
produce CH4 (g)-a waste gas
The oxidation of methane
• CH4 main ingredient in fossil fuel__________________
• The C found in CH4 borrowed from CO2
molecule removed from atmosphere MYAduring photosynthesis, it then took CH4(g)
millions of years to form and accumulate
underground
• When we burn natural gas, we return C to
atmosphere as CO2
• What would normally take millions of years to
be cycled is thus released rapidly released
Natural gas
Peat as a fossil fuel
• ____________=partially decomposed plant
matter
• Waterlogged, found in certain wetlands-e.g.
Mires and bogs in British Isles, Scandanavia, N.
Russia, some of E. Europe, N. Canada, N. China,
Amazon River basin, Argentina, N.
USA9esp.Alaska), ans some of S.E Asia
• Dark in color and only certain types of vegetation
can grow on its surface-such as Sphagnum moss
• Heterogeneous but at least 30% of its dry mass
must be composed of dead organic material
peat
• Soil that forms peat is called a _______________typically 10-40 cm thick
• Spongy---The high levels of water on peatland force
out the air that would normally be between the
particles of soil-creates anaerobic conditions—This
allows microorganisms to grow but prevents growth of
microorganisms that would help in plant matter
decomposition
• ∴ the energy rich molecules that would have been fed
upon by decomposers are left behind and transformed,
over thousands of years, into energy –rich peat.
histosol
• pH of waterlogged histosol-very acidic
• not conducive to decomposers
• this contributes to the accumulation of nondecomposed material
• within the pools of acidic water- in these wetlands
are unique organisms such as some aquatic beetles
• to be usable as fuel, cut peat is dried out to reduce
humidity. It is then cut into slabs, granules, or blocks
and moved where needed
• takes a long time to form and considered
nonrenewable energy
• when oil prices are high, peat can be a
competitive energy source
• many wetlands have been drained to replace
w/forests and farmland
• concern about wetland preservation has
hindered some harvesting of peat…but also
because of concern about unique species
• also preserve because trapped pollen can
reveal info about past climate
Oil and gas as fossil
fuels
• When left in the correct conditions, partially
decomposed peat can be further transformed
into coal
• Over millions of years, sediments can accumulate
above the peat and weight and pressure of those
sediments compress it
• Under ideal conditions, sedimentation cont. until
C-rich deposits are both under huge pressure and
exposed to high temperatures (since they have
been pushed below Earth’s surface)
• Pressure and heat cause chemical
transformations associated
w/lithification____________________
• During lithification, the molecules are compacted
and rearranged
• The hydrocarbons-long chains-are of particular
interest to industry due to the large amount of
energy they hold-ready to be released by burning
• Coal must be extracted from below ground to be
used for energy-mining
• Found in seams, where layers of sediments were
deposited, covered, and then transformed and
other twisted/deformed by geological forces over
millions of years
Which is the transformation of sediments
into solid rock
The C-H bonds hold a significant amount of energy,
and because there is many-much energy to be
released by burning
In addition to coal, the chemical transformations
underground can produce other petro products such
as crude oil and natural gas
• During the __________________________period
MYA, some places in the world that are now dry were
underwater-hosted much aquatic or marine life-inc.
algae and zooplankton
• The dry deserts of Saudi Arabia used to be under the
Tethys ocean-in the time of Pangea
• At that time, under ideal conditions for petro
formation, dead remains of organisms in the water
did not fully decompose @ the bottom of the oceaninstead forming layers of sediment w/silt
Carboniferous
• In ________-no O2 conditions-the decaying material started
to form sludge, as parts of organisms cells decayed and
others didn’t• The lipid component of cells not easily broken down-the
accumulated lipid trapped in sediments from a waxy
substance called kerogen
• Kerogen is also rich in hydrocarbons and also is transformed
by pressure and heat as sediments accumulate above it and
cause it to rearrange
• Natural production of kerogen-long process
• Over millions of years and after geological transformation,
kerogen in porous sedimentary rock becomes crude oil or
natural gas (in g state)-both being less dense than rock,
rising through the cracks to the surface
Anoxic conditions
• In order to be used by humans, petroleum
products must be trapped and pooled under
non-porous rock, preferably one bent by
tectonic movement into a dome-as seen
above-this allows large qty’s of useful gas and
oil to collect together in a productive
reservoir
• Geologists study which parts of the world
might contain exploitable gas and oil reserves
• CO2 is produced when fossil fuels are used
• Substances rich in hydrocarbons can be oxidized
using O2 gas from atmosphere when they are
burned
• Wood, animal dung, can be used-inc. for cooking
• Fresh, wet dung can be mixed w/other refuse
from a farm and put into lg container, where
methane producing microorganisms will
decompose and ferment it to produce CH4(g)• Biofuels made in biogas generator take millions
of years to form
• In efforts to reduce fossil fuel consumption, some
countries-e.g. USA and Brazil-have introduced biofuel
programs using ethanol made from crops like corn and
soybeans
• The plant material is fed to microorganisms that ferment
it and release ethanol-which is added to gasoline for carsreduces gasoline use
• Standard vehicles cannot use more than 25% ethanol
(need 75% or more gasoline)-gasohol
• Esp. adapted vehicles can run solely on ethanol
• w/a different technique, biodiesel can be made from
vegetable oil or animal fat-such as from deep-fat fryers
Limestone
• marine organisms remove CO2 from water
and some is used to make carbonate shells
• C can be in form of CO@ dissolved in water
or HCO3- ions
• Coral polyps build coral reefs-they absorb 2
ions from seawater to build the reef-HCO3and Ca 2+---forming CaCO3(calcium
carbonate)-basis for coral reef-sturdy
• Other organisms also use CaCO3 to build shells about their
bodies-mollusks-snails, clams, oysters, and mussels—when
they die their shells accumulate at bottom of ocean
• Microscopic foraminifera are usually on ocean floor and
build shells---their shells accumulating in sediment after
millions of years through lithification—forming limestone
• A bldg. material
• Carbon sequestration-taking C out of environment and
locking-up in a substance for an extended period of time—if
natural its bio- sequestration-helps maintain balance in c –
cycle
• Through biosequestration-accumulation of foraminifera
shells as sediment at bottom of ocean can trap C in
limestone for millions of years
• Making of cement by people sues limestone-releases C back
to atmosphere as CO2